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September 16, 2010

Brain Lesions, Not Old Age, Could Cause Memory Loss

by Sam Savage

Old age and memory loss have long been anecdotally linked, but advancing in years may not actually be related to those so-called 'senior moments' that often plague the elderly, according to a new study published in the online journal Neurology on Wednesday.

The study, which was completed by Rush University Medical Center neuropsychologist Robert S. Wilson, PhD, found that the same types of brain lesions that are typically associated with dementia and Alzheimer's disease could also be the cause of mild memory loss among senior citizens.

As part of the study, Wilson and his colleagues recruited more than 350 nuns, priests, and brothers to participate in the Chicago-based university's Religious Orders Study.

Each participant completed as many as 13 years of annual cognitive testing, and upon their deaths, their brains were examined for neurofibrillary tangles, cerebral infarction (stroke), and Lewy bodies--lesions typically associated with dementia.

The researchers studied the rate of change in each individual's cognitive function over time, and discovered a rapid decline over the past four to five years of life.

Pathologic lesions were said to be related to that rapid decline, according to the press release, but Wilson and his colleagues were said to be "somewhat surprised to find the pathology was very strongly predictive of the mild changes in cognitive function."

"Higher tangle density adversely affected all forms of cognition at all trajectory points. Both Lewy bodies and stroke approximately doubled the rate of gradual memory decline, and almost no gradual decline was seen in the absence of lesions," the media statement noted.

"Our study finds that Alzheimer's disease and related dementias are the root cause of virtually all loss of cognition and memory in old age," Wilson said. "They aren't the only contributing factors; other factors affect how vulnerable we are to the pathology and to its effects. But the pathology does appear to be the main force that is driving cognitive decline in old age."

"It appears these brain lesions have a much greater impact on memory function in old age than we previously thought," he added. "Our results challenge the concept of normal memory aging and hint at the possibility that these lesions play a role in virtually all late-life memory loss."

"Understanding how and when these brain lesions affect memory as we age will likely be critical to efforts to develop treatments that delay memory loss in old age," Wilson concluded.